1. Field of the Invention
The present invention relates to novel tripeptide derivatives and more particularly relates to novel tripeptide derivatives having antitumor effect and enzyme inhibition effect.
2. Prior Art
Peptides having antitumor effect are reported in Japanese Patent Kokai Nos. 120559/1982, 192349/1982, 8826/1984, 112953/1984 and the like, and bestatin is a commercially available as a peptide at present.
On the other hand, leupeptin and E-64 in U.S. Pat. No. 3,911,111 are known as peptides having inhibition effect on cathepsin B.
Since malignant tumors have indefinite variety in nature, there is a need for the development of novel antitumor agents.
It is known that cathepsin B is a proteolytic enzyme implicated in bone metabolic disorders, lysosomal disease, muscular dystrophy and metastasis of cancer. However, since most of the prior art inhibitors of cathepsin B have also inhibiting activity to other proteolytic enzymes, there is a need for the development of substances having specific inhibition of cathepsin B.